The Developmental Pharmacology Core will develop and implement assays for drugs used in patients with AIDS. These assays will be utilized to perform pharmacokinetic and drug interaction studies with dual goals of determining mechanisms of drug disposition and interaction and of providing clinical guidelines for design of optimal therapeutic regimens. This site will maintain a dynamic and flexible posture towards such studies; namely, though we plan specific projects, it is likely that availability of new drugs will provide the opportunity for important studies that cannot be anticipated at this time. Specific aims include: 1) To assess the determinants of renal excretion of DDI. 2) To assess the pharmacokinetic effects of ACT and DDI on each other. 3) To assess the elimination of DDI in patients with renal insufficiency. 4) To assess the pharmacokinetics of 8-aminoquinolones in HIV positive patients. 5) To assess phenotypes of metabolism of drugs used in patients with AIDS. 6) To assess stereoselective pharmacokinetics of drugs used in patients with AIDS.